1. Technical Field
The present invention relates to a method and apparatus for detecting and sealing leaks in a branch pipe which extends laterally from a main pipe. More particularly, the invention is concerned with detecting and sealing leaks in building service lateral sewer pipes from a point at which such pipes extend from the main sewer line. The preferred embodiment of the present invention is described in terms of sealing sewer lines; however, it is to be understood that the principles of the present invention apply equally to any pipe system wherein a branch pipe extends laterally from a main pipe.
2. The Prior Art
In recent years there has been an enormous amount of money spent on evaluation studies to quantify and detect the source of extraneous water infiltration into sanitary sewer systems. Usually, after these evaluation studies are completed, a rehabilitation program is developed to repair the points of infiltration. Such repairs are grouped into three segments of a sewer system, namely manholes, main sewer lines and building service laterals. Manhole repair is achieved by grouting, recoating and/replacement. Main sewer lines are grouted, sliplined or excavated as required. However, there is no reasonable cost-effective method for repairing building service lateral sewer lines. Excavations and other methods which have been tried have resulted in severe public relations problems for the controlling municipality with the property owners.
Several municipal sewer system projects have been completed through the rehabilitation phase, after which after-the-fact studies were conducted. Many of these studies indicated that, once the manholes and main sewer lines are fixed, the extraneous water source migrates to the building service lateral and continues leaking at a rate similar to that of the pre-rehabilitation condition.